Endotracheal tube for use during fiberoptic assisted intubation and with other intubating stylets

ABSTRACT

An endotracheal tube for use with a fiberoptic bronchoscope or other intubation stylet is described. There are ventilation holes located on the tapering section on the distal tip such that ventilation may occur while using the fiberoptic scope and such that resistance to ventilation is minimized with the scope removed. The endotracheal tube is particularly useful for difficult intubations as the distal tip is tapered which facilitates passage through the larynx.

[0001] This application is a continuaton-in-part of Ser. No. 08/546,681filed Oct. 23, 1995.

BACKGROUND OF THE INVENTION

[0002] This invention relates to medical equipment used in the fields ofanesthesiology and emergency airway management. More particularly, theinvention relates to an endotracheal tube used in conjunction with afiberoptic bronchoscope, or other stylet, to overcome intubationdifficulties.

[0003] Provision of anesthesia to patients during surgical proceduresrequires ensuring adequate respiratory function. This is most oftenaccomplished by use of an endotracheal tube (ETT). Placement of anendotracheal tube for support of respiration is a critical step in theprovision of anesthetic patient care. Placement of the ETT is performedmost often under direct visualization using a laryngoscope. However,this procedure can be difficult to accomplish due to anatomic anomalies.Often, a fiberoptic bronchoscope (FOB), or other intubating stylet, isused to overcome these instances of difficult intubations. Use of an FOBallows visualization of the upper airway structures and visualconfirmation that the trachea has been entered. Once the trachea hasbeen entered, the FOB is used as a stylet guide to place an ETT. The ETTis slid over the FOB into the trachea. Once the ETT has beensuccessfully placed in the trachea, the FOB is withdrawn and the patientcan be ventilated. Other types of stylets are also known.

[0004] The currently utilized ETTs were originally designed forintubation under direct visualization and without consideration of usein conjunction with an FOB or other intubating stylet. Their designincorporates a constant diameter tube with a leading edge. When using astandard ETT over an FOB, or other intubating stylet, the leading edgecan become impacted on the laryngeal structures causing trauma, delay,or failed intubation.

[0005] Endotracheal tubes are in general flexible breathing conduitsconstructed of medical grade plastics that are adapted to be placed inthe patient's trachea. The proximate end of the ETT has a standardfitting allowing connection to a source of pressurized gas such asoxygen and anesthetic gases. The distal end is open to deliver thesegases to the trachea and lungs of the patient. The distal end usuallyhas a side hole to aid in equal ventilation of both lungs should the ETTbe inaccurately positioned. This side hole is not intended to, nor doesit, decrease ventilatory resistance in an ETT that is correctlypositioned. The ETT typically has an inflatable bladder or balloon whichcan be inflated once the ETT is in place within the trachea. This sealsthe trachea allowing positive pressure ventilation to the lungs andprotecting them from secretions and gastric contents. During theintubation process the ETT traverses the mouth, pharynx, larynx, andtrachea of the patient and is ultimately placed in the correct positionwithin the trachea without causing damage to bodily structures. Variousdevices are available to assist with this process, the most important ofthem being the fiberoptic bronchoscope.

[0006] An FOB consists of three basic parts, a proximal control assemblywhich includes an eyepiece for viewing, an elongated shaft housingfiberoptic bundles, channels, and control wires, and a distal tipcontaining optics. In use, a high intensity light source is connectedvia the proximal control assembly for transmission through thefiberoptic bundles. The fiberoptic bundles transmit the light to thedistal tip where it is used to illuminate the object to be viewed.Optics located in the distal tip transmit the image through anotherfiberoptic bundle to the proximal control assembly where the image canbe viewed with ones eye or transmitted to a TV monitor for viewing.

[0007] In certain situations an FOB is used in conjunction with an ETTto intubate a difficult airway. This is sometimes anticipated prior toanesthetizing a patient but more often is an emergency procedure in apatient who is discovered to have a difficult airway after beinganesthetized. In either situation, an appropriate size ETT for thepatient is chosen and threaded onto the proximal shaft of the FOB. Thetip is of the ETT is lubricated with a water soluble medical lubricant.The procedure for using an FOB as an intubating stylet is the samewhether one is using a standard ETT or the described tapered ETT. Theupper airways are traversed with the distal tip of the FOB and thelaryngeal structures are visualized and identified. The distal tip ofthe FOB is advanced through the vocal cords and into the trachea. Onceentrance of the FOB into the trachea is visually confirmed, the ETT isslid down the shaft of the FOB, using the FOB as an intubating stylet.The tip of the ETT must traverse the larynx prior to entering thetrachea, and it is at this point resistance and obstruction toadvancement is not infrequently encountered. Thereafter the ETT must bepositioned accurately within the trachea and is done so either by directvisualization of the bronchi and carina (the first division of thetrachea) through the FOB, or by using predetermined norms for ETTposition and listening to breath sounds. Once positioned and thetracheal balloon inflated, the FOB is removed from the ETT. The proximalend of the ETT is then connected to a pressurized gas source and thepatient is ventilated.

[0008] Trauma from ETT placement may cause bleeding, swelling,laryngospasm, patient discomfort and hoarseness. Delayed or failedintubation can cause brain damage and/or death. This cause of delayed,traumatic, or failed intubation when using an FOB/ETT combination is notinfrequent and is documented in the anesthesia literature. For example,Ovassapian states: “In 20-30% of patients, even though the fiberscopehas entered the trachea, the endotracheal tube impinges on the larynxand cannot be advanced into the trachea. It is postulated that the tubecatches on the epiglottis or on the vocal cords or that it lodges in thepyriform sinus.”

[0009] Benumof states: “The free lumen of the endotracheal tubepredisposes the tube to move away from the the insertion cord of the FOBand catch the laryngeal structures, therefore interfering with thesmooth entrance of the tube into the trachea.” Brull et al report thatfully 13 of 20 FOB assisted intubations using a standard ETT wereunsuccessful on the first attempt. Moreover, 7 of 20 patients wereunable to be intubated using this technique (standard ETT over an FOB)on the third attempt. They state: “Furthermore, repeated attempts atpassage may result in airway bleeding, damage to the arytenoidcartilages or epiglottis, or swelling of the airway, making subsequentendotracheal intubations attempts more difficult.” Failed intubation isa significant cause of anesthetic related brain damage, death, andmalpractice litigation.

[0010] The same problem has been described when using standard ETT'sover other intubation stylets. The problem is most severe in theinstance of retrograde intubation. Retrograde intubation involvesplacing a guide wire through the crico-thyroid membrane and bringing itout through the patient's mouth. The wire is then used as a stylet guidefor an ETT. Because of the relatively large discrepancy between the thinwire (0.038-inch outer diameter) and the ETT (7-8 millimeters internaldiameter), the tip of the ETT often impinges upon the larynx.

[0011] Several ETTs and other devices have been designed for specificfunctions and to overcome specific difficulties related to the difficultairway. For example, Ring, Adair, and Elwyn, in U.S. Pat. No. 3,964,488,seek to overcome the problems of ETT kinking and obstruction byincorporating a preformed angle in the shaft of an ETT. Carden, in U.S.Pat. No. 4,041,936, describes an ETT designed for use during fiberopticbronchoscopy of the lungs which simplifies the procedure. Vilasi, inU.S. Pat. No. 3,968,800 describes a “Device For Insertion Into A Bodyopening.” One embodiment is an endotracheal tube with an adjustableexternal circumference which seeks to overcome the need to stockmultiple size ETTs and to supplant the need for a tracheal balloon.Adair, in U.S. Pat. No. 5,329,940 describes an “Endotracheal TubeIntubation Assist Device” which couples an FOB with a television monitorto assist with the problem of difficult intubation. Cook Medical marketsa retrograde intubation kit, which also seeks to address the problem ofthe difficult airway.

[0012] Vilasi describes a device which generally suffers fromcomplexity, and is therefore more expensive to manufacture, is more userdependent in its correct operation and application than a simplerdevice, and is more time consuming to operate than a simpler devicedesigned for the same purpose. Using this device as an ETT would raisesafety issues as well. One can see that an FOB placed through thisdevice in the non-expanded configuration would significantly interferewith ventilation. This is a serious drawback of the design for use withan FOB, as the ability to visualize anatomic structures whilemaintaining sufficient ventilation is often necessary or desirable, suchas when one is checking for correct placement of the ETT within thetrachea. This is accomplished by using an FOB bronchoscopy adaptor whichallows the FOB and pressurized gases to be delivered through the ETT atthe same time. Attempting to intubate a patient or position the deviceby moving it in the expanded configuration (intentionally orunintentionally), within the trachea, would risk laceration of thetrachea or other upper airway structures, a potentially disastrouscomplication. Using the device of Vilasi in solelyrthe closedconfiguration would be limited by the increase in resistance to gas flowcaused by narrowing the distal end according to Poiseuille's law whichstates resistance is inversely proportional to the inside radius of theconduit to the 4th power. Hence, small decreases in ETT size give largeincreases in airway resistance. Therefore, the more useful the device ofVilasi is for intubating difficult airways over a stylet, the lessuseful the device becomes as a breathing conduit due to the increase inairway resistance.

[0013] Adair utilizes a standard ETT in conjunction with his device forassisted intubations. The standard ETT depicted in Adair is not tapered,has a leading edge, and an opening at the distal end which aids in theequal dispersion of oxygen into the lungs. Its use with a standard ETTis therefore subject to the same problems described above, stemming fromsize discrepancy and the leading edge.

[0014] Others in the art teach using a standard ETT for instances whenan intubating stylet of one type or another are used. Examples ofintubating stylets include FOB's, tracheal tube changers, tracheal tubeintroducers and guides, and wires used in retrograde intubation kits.For example, the ETT illustrated in the retrograde intubation andtracheal tube changer literature is of standard design. Olympus, theleading FOB manufacturer, depicts a standard ETT in their literature.

[0015] The problem of the tube tip catching on the laryngeal structuresis in part a function of the discrepancy between the diameter of theintubating stylet and the ETT, causing the leading edge to be orientedincorrectly as the distal tip approaches the larynx. Attempts toovercome this problem have been made. For example, Cook Medical includesan obturator sheath which functions as a spacer in its retrogradeintubation kit. The spacer is fitted over the wire after a retrogradeintubation wire has been placed, after which the ETT is slid down thecombined-wire/spacer assembly. This adds another step and time to aprocedure in which time is of the essence but is deemed necessary toaddress the size discrepancy problem. It also does not necessarily solvethe problem, only lessens it by degree. Brull et al. describe havinggreater success using a spiral wound, more flexible ETT than a standardETT for fiberoptic assisted intubations. They postulate that improvedperformance was due to the increased flexibility of the ETT, and to aless acute angle of the leading edge relative to the longitudinal axisof the ETT as opposed to the standard ETT. They also note that theSpiral Wound ETT was 10-20 times the cost of a standard ETT and that 5%of the time intubation using the spiral wound ETT and an FOB wasunsuccessful in their series. The described ETT of the present inventionrepresents an improvement over the prior art for this purpose.

SUMMARY OF THE INVENTION

[0016] The objectives of the invention are accomplished by providing adistally tapering endotracheal tube, with no significant leading edge,that has ventilation holes placed on the tapering portion of the ETT tomitigate what would otherwise be a prohibitive increase in theresistance to gas flow. Additionally, the tube is typically constructedof polyvinyl chloride and otherwise manufactured in the same fashion asa standard ETT. The tapered ETT may be constructed of various sizes tomatch patient needs. Similarly, the distal aperture for passage of theFOB may be of various sizes to complement the diameter of the FOB inuse. The ideal aperture would be only slightly larger in diameter thanthe FOB in use, such that the ETT slides easily upon the shaft of theFOB yet is closely contoured to the shaft in order to prevent difficultyof passage of the ETT at the level of the larynx. The ventilation holesare distal to the tracheal balloon and are preferrably placed mainly orwholly on the tapered portion of the ETT. This allows adequateventilation when the FOB is in use and protruding through the distalaperture. Ventilation is accomplished by attaching a fiberopticbronchoscopy adaptor to the proximate end of the ETT which allowsconnection to a pressurized gas source and passage of an FOB through adiaphragm.

[0017] This new feature can be critical in the following situations.Difficult intubations are those instances most likely to lead toaspiration of gastric contents into the lung. This will cause hypoxemiawith its attendant problems of cardiovascular instability and braindamage if not reversed. Aspiration is best diagnosed by viewing thebronchi with an FOB, looking for bile, food particles, and erythema.While one is interested in making the diagnosis rapidly in order toinstitute the correct therapy, one does not want to interruptventilation which will exacerbate hypoxemia. Additionally, whenhypoxemia occurs, one of the first maneuvers is to check for correctplacement of the ETT, as misplacement is a frequent cause of hypoxemia.This ETT will allow continued ventilation while the FOB is in use andwill address this dilemma.

[0018] With the FOB removed from the ETT, the combination of side holesand the distal aperture provide for ventilation through the ETT withouta significant increase in ventilatory resistance relative to a standardETT. Thus, this invention accomplishes the objectives of makingdifficult intubations safer, less traumatic, and quicker when using thisETT in conjunction with an FOB or intubating stylet, but without asignificant increase in ventilatory resistance that would otherwiselimit its usefulness. Additionally it allows ventilation through atapered ETT while the FOB is in use and so has the added feature ofcombined ventilatory support and diagnostic capacity.

[0019] Accordingly, there are several objects and advantages of myinvention.

[0020] One advantage provides an endotracheal tube that when used inconjunction with a fiberoptic bonchoscope, or other intubating stylet,will result in safer intubations.

[0021] Another provides an endotracheal tube that when used inconjunction with a fiberoptic bronchoscope, or other intubating stylet,will result in less trauma to the airway during intubation.

[0022] Yet another benefit of my invention is to provide an endotrachealtube that when used in conjunction with a fiberoptic bronchoscope willresult in fewer instances of failed intubations.

[0023] Yet another benefit of my invention is to provide an ETT thatwhen used in conjunction with an FOB or other intubation stylet willresult in quicker intubations.

[0024] Another benefit of my invention is to provide an endotrachealtube that will facilitate intubations over an FOB or intubating styletyet will not significantly increase resistance to ventilation when theETT is in use with the FOB or stylet removed.

[0025] Another benefit of my invention is to accomplish the above goalsby providing an ETT which is simple to use and cost effective tomanufacture.

[0026] Further objects and advantages of this invention will becomeapparent from a consideration of the drawings and ensuing description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the drawings, closely related figures have the same number butdifferent alphabetic suffixes.

[0028]FIG. 1A is a perspective view of the endotracheal tube.

[0029]FIG. 1B is a detailed drawing of the distal end of the ETT showingthe novel features of the invention in a perspective view.

[0030]FIG. 2 is a cross section of a human head showing the endotrachealtube in use with a fiberoptic bronchoscope (the proximal control andeyepiece assembly is not shown).

PREFERRED EMBODIMENT OF THE INVENTION

[0031] Referring now to FIGS. 1-2, an endotracheal tube 16 for useduring fiberoptic assisted intubations and with other intubating styletsis shown. The manner of using the tapered ETT 16 utilizes the sametechnique now being used with conventional ETT's for FOB assistedintubation of the trachea. Specifically, one first places the shaft ofthe FOB 20 (proximal control assembly not shown) through the lumen ofthe ETT 16. Standard features incorporated include a pilot balloon 12that communicates with a tracheal balloon 10 via tubing 14. The combinedapparatus is placed in the pharynx and the laryngeal structures arevisually identified with the FOB 20. The FOB 20 is passed through thevocal cords into the trachea under bronchoscopic visualization. The ETT16 can now be slid down the shaft of the FOB 20 into the trachea usingthe shaft of the FOB 20 as a stylet guide as depicted in FIG. 2. Thislast maneuver is often where difficulty is encountered with aconventional ETT due to its non-tapered shape and leading edge. Notuncommonly, the leading edge will impinge on the laryngeal structures.This may cause trauma, and or delay, and or abandonment of theprocedure. The tapered tip 8 of the described ETT is less traumaticallyand more quickly placed, with greater success rates due to thecombination of (a) a smaller diameter distal end 8 which is more closelycontoured to the shaft of the FOB 20, and (b) the absence of a leadingedge. A tapered tip should be understood as a structure whose distal endis significantly smaller in diameter than that of the tube. There is noprecise dimensional relationship between the tube and distal enddiameters, although an example is provided below. The emphasis here isin avoiding a leading edge and in reducing the size of the ETT'S distalend so that the previously discussed problems are minimized oreliminated, all while still providing respiratory function with nocomplicating resistance.

[0032] The ventilation holes 6 situated on the tapering portion of theETT allow ingress and egress of respiratory gases without undueresistance to flow. They do so by a) increasing the cross sectional areaavailable for passage of respiratory gases, and b) when the ETT 16 is inplace within the trachea, by allowing enough clearance between thetracheal wall and the ventilation holes 6 such that gas exchange is notsignificantly impeded. Placing the ventilation holes 6 on the taperedportion of the distal end 8, as opposed to the non-tapered portion ofthe ETT 16 distal to the balloon 10, also removes the holes 6 from theproximity of the balloon 10 and thus the possibility of obstruction dueto balloon 10 herniation. Less preferred embodiments place the holes 6partially on or just off the tapered portion of the tube. Herniation canoccur when the balloon 10 covers and thus obstructs ventilation throughholes 6 due to overexpansion. All functions that may be performed with aconventional ETT, e.g. passage of a suction catheter or application ofpositive end expiratory pressure, can be performed with the ETT 16.Additionally, ventilation can be performed through the holes 6 while theFOB 20 is in use and protruding through, and therefore obstructing, thedistal aperture 4. This would be impossible with a standard, non-taperedETT whose internal diameter is only slightly greater than the FOB 20.

[0033] A preferred embodiment of a fiberoptic endotracheal tube 16 isillustrated in FIG. 1A. A standard universal adaptor 18 is seated into aunitary endotracheal tube 16. The ETT 16 is manufactured by a plasticinjection technique using a soft medical grade polymer such as polyvinylchloride in the same fashion as are standard ETT's. The most usefulsizes for the ETT 16 (in adults) are from 6.5 mm to 8.5 mm internaldiameter, increasing in 0.5 mm increments. FOB 20 are manufactured witha variety of standard shaft sizes, 3.7 or 4.0 mm diameter being the mostversatile and common for adults. Therefore, for example, with a 3.7 mmFOB 20 protruding through the distal aperture 4, of a 8.0 mm ETT 16,fully 79 percent of the cross sectional luminal area of the non-taperedportion of the ETT 16 remains available for ventilation. The remainingcross sectional luminal area is 39.5 square millimeters, which isslightly greater than a standard 7.0 ETT (38.47 square millimeters).Endotracheal tubes for pediatric use, for example, would beproportionately smaller.

[0034] Utilizing an ETT with a distal aperture 4 approximately 0.3 mm indiameter greater than the FOB 20 used as a stylet allows for smoothaction of the ETT 16 upon the FOB 20. Therefore, for use with a 3.7 mmFOB , the distal aperture 4 can be manufactured with an internaldiameter of 4 mm. One can see, for example, using an ETT 16 of standardinternal diameter 8.0 mm allows a 50% reduction in distal aperture 4internal diameter relative to a non-tapered ETT. These dimensions are byway of example only. They are subject to variance based upon preferencesof manufacturers and physicians. The principle requirement in thedifferent diameters of the ETT and the FOB is smooth action between thetwo.

[0035] The distance from the distal tip of the ETT 16 to the distalborder of the balloon 10 when inflated is variable and is a function ofstyle of taper employed, i.e. straight or nipple shape. In general thedistance is approximately 22 mm, which is currently utilized in astandard adult ETT.

[0036]FIG. 1B is a detailed illustration including the features of thisinvention in a preferred embodiment. The distal tapered end 8 is shownterminating in a circular aperture 4 which is oriented perpendicular tothe long axis of the endotracheal tube. Therefore, the ETT 16 does nothave a leading edge. The ventilation holes 6 are situated on thetapering portion of the distal tapered end 8.

[0037]FIG. 2 is an illustration of the endotracheal tube 16 in use witha fiberoptic bronchoscope 20 (control and eyepiece assembly not shown),during the intubation process.

[0038] While my above description contains many specificities, theseshould not be construed as limitations on the scope of the invention,but rather as an exemplification of one preferred embodiment thereof.Many other variations are possible. For example, the distal aperture 4need not be perfectly perpendicular to the long axis of the ETT andconsequently need not be perfectly circular. The ETT itself need not beperfectly circular for that matter and could be elliptical, for example.The requirement is there not be a significant leading edge such thatthere is a risk of the leading edge impinging on the larynx withregularity. The aperture 4 may be of various sizes and shapes. Thetapered end 8 can be of various shapes as opposed to the mammaliannipple shape shown in the drawings. It could be, for example, atruncated conical section, with or without a generally cylindrical,short guide at the very tip of the taper.

[0039] The ventilation holes 6 can be of various number, size, shapes,and locations, etc., so long as the structural integrity of the ETT ismaintained. Thus, for example, there could be two, three, or four holeson the tapered portion. Those holes could be circular, elliptical, oreven triangular. In the instance where the tapered tip comprised amammalian nipple, the hole may even be located on an untapered portionof the nipple. Still another embodiment of the invention contemplatesthat the ventilation holes are disposed on the constant diameter portionof the ETT, between the tracheal balloon and the tapered tip. Thus thescope of the invention should be determined by the appended claims andtheir legal equivalents, rather than by the examples given.

What is claimed is:
 1. An endotracheal tube for use with a fiberopticbronchoscope or other intubating stylet, comprising: a) a unitary tubewith a proximal portion of generally constant cross section; and b) atapered end portion of said tube, disposed distally on said tube, saidtube having at least one hole situated on said tapered distal end,whereby ventilation is accomplished without undue resistance.
 2. Thetube of claim 1 , further comprising a tracheal balloon disposed on saidtube generally proximate to said tapered end.
 3. The tube of claim 2 ,wherein said tapered end is configured as a mammalian nipple.
 4. Thetube of claim 2 , wherein said tapered end is configured as a truncatedconical section.
 5. An endotracheal tube adapted for use with afiberoptic bronchoscope, comprising: a) a tracheal balloon; b) a unitaryflexible tube, passing through said balloon, comprising a proximalportion of generally constant cross section, said proximal portion beingdisposed on one side of said balloon; c) a tapered distal portion ofsaid flexible tube, disposed on said balloon oppositely of said proximalportion; and d) at least one ventilation aperture disposed on saidflexible tube distally of said balloon.
 6. The endotracheal tube ofclaim 5 wherein said ventilation aperture is disposed on said tapereddistal portion.
 7. The endotracheal tube of claim 7 wherein said tapereddistal portion is generally configured similar to a mammalian nipple. 8.The endotracheal tube of claim 7 wherein said tapered distal portion isgenerally configured as a truncated conical section.
 9. The endotrachealtube of claim 5 wherein said ventilation aperture is disposed partiallyon said tapered portion and partially on a constant cross-sectionedportion distal to said balloon.
 10. An endotracheal tube for use with afiberoptic bronchoscope or other intubating stylet, comprising: a) atracheal balloon; b) a tube disposed proximal to the balloon forventilation and for relative movement between the tube and the stylet;c) a tube disposed distal to the balloon, having an exterior wallsurface and an interior wall surface defining a lumen for ventilationand for relative movement between the tube and the stylet, the lumenhaving an axis disposed generally along its centerline; d) a ventilationaperture, disposed in the distal tube for ventilation and for relativemovement between the tube and the stylet; and e) a tapered tip disposedon the distal tube and distal to the balloon, whereby the exterior wallsurface of the tube tapers toward the lumen axis to avoid forming asignificant leading edge.
 11. The endotracheal tube of claim 10 ,further comprising a second ventilation aperture disposed in the distaltube more proximal to the balloon than the first ventilation aperture.12. The endotracheal tube of claim 10 , wherein the tapered tip is atruncated cone.
 13. The endotracheal tube of claim 10 , wherein thetapered tip further includes a guide tip.
 14. The endotracheal tube ofclaim 10 , wherein the ventilation aperture is perpendicular to the axisof the lumen.
 15. The endotracheal tube of claim 11 , wherein the secondventilation aperture includes an axis defined by centers in openings inthe interior and exterior wall surfaces.
 16. The endotracheal tube ofclaim 15 , wherein the axis of the second aperture is perpendicular tothe axis of the distal endotracheal tube.
 17. The endotracheal tube ofclaim 10 , wherein the proximal and distal tubes comprise a unitarytube.
 18. The endotracheal tube of claim 10 , wherein the tapered tip isa mammalian nipple.